Serial transmission has increasingly been employed to achieve high-speed signal transmission within information processing apparatuses as well as between information processing apparatuses and their peripherals. PCI Express (Peripheral Component Interconnect Express), hereinafter abbreviated as PCIe, and SAS (Serial-Attached SCSI (Small Computer System Interface)) are major standards for such high-speed serial transmission. These standards use a plurality of serial transmission paths bundled together, providing high-speed data transmission.
As technology using PCIe, the following information transmission apparatus, for example, has been proposed. Upon detecting an energy-saving switchover event, the information transmission apparatus enters a power saving mode by putting one lane amongst a plurality of lanes into an effective state while placing the remaining lanes into an idle state.
Japanese Laid-open Patent Publication No. 2010-147702
Sudden communication failure sometimes occurs when communication between communication circuits by high-speed serial transmission described above is in progress. Such communication failure may be attributed to aging degradation of a capacitor, such as an alternating current (AC) coupling capacitor, on a transmission path. Performing diagnosis to detect an abnormality sign of forthcoming communication failure may be considered as one way of dealing with this problem; however, in order to perform the diagnosis, the communication needs to be interrupted.